The present invention relates to lanthanide series-bisphthalocyanine complex compounds expected to generate excellent electrochemical characteristics such as electrochromism etc., wherein said compounds comprise chemically and thermally stable side chains effective for the development of functional film due to the generation of solubility and liquid crystallization in a solvent.
Hitherto, it has been expected that electrochromic substances may be put on display in practice under consideration that said compounds show discoloration by applying voltage thereto. Particularly, lutetium (or lanthanide series)-bisphthalocyanine complexes are being closely examined as one of few electrochromic substances having multi-color property. In general, phthalocyanine compound is insoluble in a solvent and the practicality thereof was limited, though it is easy to synthesize. Simon et al. have solved the aforementioned difficulty by applying eight long-chain alkoxyethyl groups to the circumference of phthalocyanine and further have proved that said substance exhibits liquid crystallization. Furthermore, the lanthanide series complexes not only exhibited an electrochromic property but also excellent electrochemical property such as an organic semi-conductor property. (For example, please see to French Patent "Brevet Francais" 84/19,348, FR 2,574,806). However, since the complexes have a hetero atom at the side chains thereof, said side chains become reactive and therefore stability as an electrochromic substance was a problem to be solved.
In order to solve the aforementioned problem, the present invention to mind provides electrical and thermal stabilities by introducing long chain alkyl group having no hetero atom as the side chains of lanthanide series bisphthalocyanine complexes. As a result of studies on phthalocyanine derivatives, the present invention has been achieved through various experiments by demonstrating that the lanthanide series complexes of octa (alkyl) phthalocyanine substituted at the 2, 3, 9, 10, 16, 17, 23 and 24 positions (shown by a general formula (1) below) with a long chain alkyl group have properties.
Hereinafter, an outline thereof will be described. ##STR1##
The general formula (1) is constituted in a manner such that two phthalocyanine rings are coordinated in a state of sandwiching the lanthanide series. In the formula, R is an alkyl group having 4-30 carbon atoms, and Ln is lanthanide series (La-Lu) and Yttrium. This empirical formula is written as (R.sub.8 Pc).sub.2 Ln where Pc represents phthalocyanine.
An exact structural formula (metal free) of octa-substituted phthalocyanine which is the ligand is shown as follows: ##STR2##
The above phthalocyanine is shown hereinafter as simply as possible; ##STR3## wherein N atoms shown therein are N atoms of four pyrrole rings.
By employing the above simplified phthalocyanine model, the general formula (1) may be shown as follows: (Ln: Lanthanide series ions (La-Lu) and yttrium). ##STR4##
Free metal octasubstituted phthalocyanine was synthesized based upon the method of Simon and Ohta etc, New J. Chem., 12, 751 (1988). In detail, Grignard reagent prepared by alkylbromide and metal magnesium was reacted with orthodichlorobenzene and the dialkylbenzene 3 thus obtained was brominated so as to obtain dibromide 4 (FIG. 1).
Then, said dibromide 4 was reacted with copper (1) cyanide so as to obtain dicyanobenzene derivatives 5 (FIG. 1). Thereafter, metal free phthalocyanine was obtained under reaction in the presence of a base. Regarding the synthesis of phthalocyaninate) lutetium complex, a conventional well known method (e.g. Chem. Phys. Lett., 22, 124 (1985) by Simon et al.) was employed. In detail, phthalocyanine was treated with the base and thereafter was reacted with acetic lanthanide so as to obtain lanthanide series-bisphthalocyanine complexes shown in the general formula (1). R shown in the general formula (1) is an aliphatic alkyl group C.sub.4 -C.sub.30 and R=C.sub.8 -C.sub.18 is preferable in view of the treatment. (C: the number of carbon atoms). In the case where R=C.sub.12, furthermore, the general formula (1) showed a monotropic and discotic liquid crystal phase. Further, the general formula (1) wherein R=C.sub.8, C.sub.12 and C.sub.18 was generally of green color, but electrochromism showed red color at +0.29 V and blue color at -0.17 V.